A schematic model that links the slab hole with other physiographic features. The view is from the east, and theJuan de Fuca slab is shown in blue. The propagator wake (bold gray line underneath Oregon) causes a weakness in the slabalong which a tear is propagating. The High Lava Plains (contours in Oregon) lie above the southern edge of theslab hole. The Gorda slab rotates clockwise, causing intraplate seismicity in the Gorda region.

Untangling Oregon Volcanism


Most of Oregon is igneous rock. Pretty recent igneous rock, as geologists measure time. It’s almost embarrassing. While some of it is pretty well understood, parts of all that volcanism are unexplained. The stratovolcanoes of the High Cascades? Subduction of the Juan de Fuca Plate and Pacific Plate. The lava that flowed into the Pacific…